Synlimb: A Prosthetic to Control Music with the Mind

Even if our ultimate goal is to restore lost limbs (or their basic functionality if they are still present), we must acknowledge that the progress in prosthetic development has been remarkable. At the same time, some models essentially behave as electronic platforms that cry out to be hacked, and that's exactly what Bertolt Meyer, a psychology professor, DJ and electronics enthusiast, did. Thanks to his Synlimb module, he can transmit commands and control a modular synthesizer at a speed far superior to that allowed by his prosthetic.

Many have turned Cyberpunk 2077 into a kind of meme with strange hacks and electronics tricks, but the central idea of a much closer relationship with technology is not at all far-fetched, and there are special cases that deserve our attention and admiration. One such case is Bertolt Meyer, a psychology professor who was born without his left forearm. Meyer uses an advanced prosthetic that works wonderfully, although it suffers from some natural limitations.

The Speed Problem

It turns out Meyer is also a DJ, and his prosthetic's response speed (not to mention the lack of precision when manipulating small objects) is not entirely suitable for the rapid changes a modular synthesizer requires. However, those changes can be made with small voltage variations injected through a plug, almost like a remote control. Now, Meyer's prosthetic works with two electrodes that detect muscle activity, and when he recorded their values with a multimeter he discovered they were too low, in the order of 1.5 volts. What he needed from there was a way to amplify that voltage...

The Solution: KOMA Elektronik Field Kit

Meyer doesn't consider himself an engineer, but he has some basic electronics knowledge. The DJ discovered the solution hidden in his "KOMA Elektronik Field Kit" (which anyone interested can buy today for 230 euros), since it includes an amplification function. When he contacted the manufacturers (Wouter and Christian) and explained what he wanted to do, he received a copy of the circuit in less than five minutes. Meyer managed to build a prototype compatible with one of his electrodes, but the story doesn't end there.

Taking advantage of his free time, Christian from KOMA decided to design a custom circuit so Meyer could use both electrodes at once. Meyer's husband (Daniel) took charge of creating a mount with a 3D printer, and the rest was a matter of connecting the module to the prosthetic (the interface was extracted from an old hand that no longer worked).

In this way, Meyer manages to establish a link between his mind and the amplifier, passing through muscles, electrodes, and the module dubbed Synlimb. Of course, it still requires some practice, but he's so used to generating signals with his muscles that training should be minimal.

Bertolt Meyer on YouTube: Click here